OPIUM - OPAL Purity Inference based on a Unified lattice Model

Overview

OPIUM performs inference of method purity (i.e. deterministic behavior and absence of side effects) on Java (bytecode) projects. Its results can be used for bug detection and program comprehension.

OPIUM was described in A Unified Lattice Model and Framework for Purity Analyses published at ASE 2018. Purity results for the JOlden benchmark are available here.

Obtaining OPIUM

A version of OPIUM ready to to be executed can be downloaded here.

A current state of OPIUM can be obtained from OPAL's repository where OPIUM is implemented by class org.opalj.support.info.Purity.

Running OPIUM

OPIUM uses a command line interface. To simply analyse an application, use
java -jar OPIUM.jar -cp <path to your application.

Use java -jar OPIUM.jar to print a list of additional parameters that OPIUM understands.

OPIUM can be used to analyze Java bytecode up to and including Java 10.

Latest improvements

The following changes have been made to OPIUM and its purity model since the paper was published:

• A new purity level, Compile Time Purity, was added to identify methods that do not use global state (i.e. static fields) with values that are constant during one execution of a program but may differ between different program executions.
• External Purity was removed in favor for a more fine-grained representation of Contextual Purity: Contextual Purity now includes the set of all parameters that may be modified by the method. External purity (as still reported separately by OPIUM) comprises all contextually pure methods where that set contains just the implicit this reference (i.e. instance methods for which the set of modified parameters contains just the value 0).
• OPIUM now uses parallel execution on as many cores as available, significantly speeding up purity inference.